What's the deal with all the trays and baskets?

Two big reasons for putting all work on our work shelf in trays or baskets:
1) It allows the child to carry the work all at once from the shelf to the table or carpet. Some work (anything involving water!!) is tablework and other work can be done on a rug. Have a large basket or shelf in the room where you store one thin rug for each child. Teach children to roll these up from left to right before storing in their spot.
-children should be taught to carry baskets or trays with both hands.
-teach children to restore the work to the same spot where they got it
-I teach that only one basket or tray of work may be out for each child at one time. If they want to work with something else, they clean up and put the tray they were using back first.
2) It contains the work. All work should be kept on the tray (as long as this is feasible with the particular work) and this solves the problem of multiple children getting items mixed up, keeps pieces from being all over the floor or room, and helps maintain and teach organization.